Nitrostyryl dye bases and vinylogs thereof derived from 2-cyanomethylazoles



United States Patent NITROSVTYRYL .DYETBAsnsg'ANDvINYLoGs HER F E I ED anon a-cYANmuE'rH-p YLAZOLES No Drawing. Filed Sept. 24, 1957, Ser. No. 685,803 6 Claims. cl. 260-240 This invention relates to nitrostyryl dyes and vinylogs thereof derived from Z-cyanomethylazoles and to a process for preparing same.

It is known that styryl dye bases can be prepared by elimination of alkyl halide from the styryl dye salts and in this connection reference is made to US. Patent 2,-

169,434. The method thereof comprises heating the styryl dye salts in a high boiling tertiary amine such as diethylaniline wherein the styryl dye is dequaternized to to yield the styryl base.

It is ,further known that styryl bases may be synthesized directly by condensing a benzaldehyd-e with a hetero} cyclic ring system containing a reactive methylene group in the 2- or 4-position. i A

I have now found that'styryl bases and their higher vinylogs can be produced by reacting a heterocyclic base having a 2- or 4-cyanomethyl group with a nitrobenzaldehyde or higher vinylog thereof in the presence of a basic condensing agent.

The resulting new styryl bases are excellent desensitizers for theproduction of direct positive photographic emulsions and in this connection reference is made to the application of Dersch and Doorenbos .filed' on even Patented Sept. 20, 1960 wherein Z, A and m have the values set forth above with a benkaldehyde' containing at least one nitro groupin the phenyl ring. Various substituted nitrobenzaldehydes date herewith and entitled, .DirectP-ositive Photographic Emulsion, Serial Number-685,817,

The aforesaid styryl bases and the preparation of the same constitute the aim and purpose ofthis invention.

The styryl dye-bases contemplated, herein can be represented by the following genenal. formula: I. .z ON I i No,

oxazole, selenazole, benzoselenazole, '3,3-dialkylindole- -nine; e.g., 3,3-dimethylindolenine, 3,3,5-trirnethylindole- 'nine, wherein said heterocyclic :n-uclei can containsuch substituents as halogen, e.g;,.chlorine, bromine, etc.; hydroxy, amino, nitro, etc. I tpgepare' the styryl 'dye' bases of: Formula densing a heterocyclic base having a 2- or 4-cyanomethyl gronpas represented by the following formula;

I byconcan be reacted with the compounds of Formula II of which the following list is typical.

o-Nitrobenzaldehyde m-Nitrobenzaldehyde p-Nitrobenzaldehyde V i t a. 2. 4-di benza yde 3,4 dinitrobenzaldehyde 4-.chloro-2-nitrobenzaldehyde 4-bromo-Z-nitrobenzaldehyde 3-chloro-4-nitrobenzaldehyde 3-hydrox-y-2-nitrobenzaldehyde 4-amino-2-nitrobenzaldehyde 4-chloro-3-nitrobenzaldehyde 5-ehloroQ-nitrobenzaldehyde 3-hydroxy-4-nitrobenzaldehyde The condensations for preparing the aforesaid styryl dye bases'are'advantageouslycarried out in the presence of a basic catalyst (acid binding agent) such as a tertiary organic amine of the trialkylamine type, i.e., trimethylamine, triethylamine, tri-n-propylamine, etc.; a secondary organic amine, i.e., piperidine, pyrrolidine, etc.; and mineral alkalines, i.e., sodium or potassium carbonate. Solvents that can be advantageously used include the lower alcohols of the formula: C H OH, wherein n is a positive integer of from 1 to 4.

The requisite az/oleace'tonitrile intermediates are pre pared according to methods reported in the chemical literature. The syntheses of 2- and 4-cyanomethylquinolines are described by P. Jungmann in Angew. Chem, A, 72 (1948), wherein N-methyl-N-cyanoaniline is reacted with quinaldine or'lipidine in the presence of NaNH NaNHMePh catalysts to produce 2- or 4-quinaldineacetonitrile. To prepare pyridineacetonitriles, 2- or 4-pyridineacetarnide is heated with phosphorous pentoxide to 'yi eid the corresponding nitrile derivative. Other azoleacetonitriles are obtained by reacting an aromatic amine, of the following formula: 7 v

I 2- (u-cyano-p-nitrostyryl benzimidazole CH- I NO1 at n, a solution .of 157g. 0.01 mole) "of '2 benzimidra zoleacetonitritle'and 1.51. 'g. (0191 mole) ofp-nitrobenz- "aldehyde in 20 m']. of ethanol was added 3 1 of pipe r i- 3 dine. The mixture was refluxed for 1 hour. A yellow dye began to precipitate shortly after the mixture began to reflux. The mixture was cooled, filtered, washed with ether, and the crude dye crystallized from a dimethylformarnide ether mixture. The yield was 1.08 g. and melted at 34-1-350 C., maximum absorption below 400 my.

EXAMPLE 11 V v 5 (6) -chl0r0-2-(u-cyano-m-nitrostyryl) benzimidazole H I l NO; ON I ml. of methanol was added 0.5 ml. of piperidine.

To a solution of 1.92 g. (0.01 mole) of 5(6)-chloro-2- benzimidazoleacetoni-trile and 1.51 g. (0.01 mole) of mnitrobenzaldehyde in ml. of ethanol was added 1 ml. of piperidine. The mixture was refluxed for 1 hour. A yellow dye began to precipitate shortly after the mixture began to reflux. The mixture was cooled and the product filtered, washed with ether and boiled twice with methanol, cooled, filtered and dried. The yield was 1.05 g. and melted at 308311 0., maximum absorption below 400 m EXAMPLE III 2- a-cyano-m-nitrostyryl) benzimidazole H 111 NO 1 To a solution of 3.7 g. (0.025 mole) of 2-benzimidazoleacetonitrile and 3.8 g. (0.025 mole) of m-nitrobenzaldehyde in 40 ml. of absolute ethanol was added 10 drops of triethylamine. The mixture was refluxed for 1 hour, cooled and the solid filtered off and recrystallized from acetonitrile. The yield was 1.68 g. and melted at 263-268" 0., maximum absorption below 400 m EXAMPLE IV 2-( u-cyano-p-nitrostyryl) -5 (6) -methylbenzimidazole To a solution of 1.71 g. (0.01 mole) of 5 (6)-chloro-2- benzimidazoleacetonitrile and 1.51 g. (0.01 mole) of pnitrobenzaldehyde in 30 m1. of methanol was added 1 ml. of piperidine. A yellow dye formed immediately and separated on heating. The mixture was heated for 30 minutes, cooled and filtered. The solid was washed with ether and crystallized from dioxane. The yield was 1.5 g. and melted at 265-270 C., maximum absorption below 400 mu.

EXAMPLE V 2-( a-cyana-m-nitrostyryl) -5 (6) -methylbenzimidaz0le This dye was prepared in the manner described in Example IV on a 0.01 molar 'scale with m-nitrobenzalde- 'hyde being substituted for p-nitrobenzaldehyde. The 'yield was2.1 g.

4 EXAMPLE VI 2- [I-cyano-4-(o-nitrophenyl) -1 ,3-butadienyl] -5 (6) methylbenzimidazole ILI ON o-d='oH-orr=orr 1 CH To a solution of 1.0 g. of o-nitrocinnamaldehyde and 1.0g. of -5(6)-methyl-2-benzimidazoleacetonitrile in 20 The solution was re-fluxed for 10 minutes. It was cooled and the product filtered ofi triturated with hot isopropyl alcohol, Washed with ether and dried. The yield was 1.1 g.

EXAMPLE VII 2-( u-cyano-p-nitrostyryl) -5 (6) -meth0xybemzimidaz0le 2-( a-cyano-p-nitrostyryl) pyridine This compound was prepared according to the procedure of Example I but using 2-pyridineacet0nitrile in place of 2-benzimidazoleacetouitrile.

EXAMPLE IX 2-(a-cyan0-p-nitrostyryl) quinoline This compound was prepared according to the procedure of Example I but using 2-quinolineacetonitrile in place of 2-benzimidazoleacetonitrile.

EXAMPLE X 2 a-cyano-p-nitrostyryl benzothiazole N. (IN/o-o 1 This compound was prepared according to the procedure of Example I but using 2-benzothiazoleactonitrile in'place of Z-benzimidazoleacetonitrile.

I claim:

1. A polymethine compound of the following general formula:

,;Z CN N0:

wherein R is selected from the class consisting of hy- 5. A polymethine compound of the following formula: drogen, halogen, hydroxy, amino and nitro groups, n H

represents an integer of from 1 to 2, m, represents an integer of from 1 to 2, A represents a methine group and benzimidazole, benzothiazole, pyridine and quinoline 1'4 9N Z is a resldue selected from the class consisting of 5 nuclei. NO

2. A polymethine compound of the following formula; 6. A polymethme compound of the following formula:

ON Q o a=cn@ m References Cited in the file of this patent 3. A polymethine compound of the following formula: UNITED STATES PATENTS H 2,255,077 Middleton Sept. 9, 1941 2,345,094 Brooker et al Mar. 28, 1944 N 0N N01 2,669,515 Kendall et a1. Feb. 16, 1954 1} Q 2,794,802 Horwitz June 4, 1957 C- =OH 91 FOREIGN PATENTS 824,818 Germany July 8, 1949 4. A polymethine compound of the following formula:

H OTHER REFERENCES I Mees: The Theory of The Photographic Process, p.

\ ON 1046, The Macmillan 06., New York 1942 C=CH-NO, 1 c 

1. A POLYMETHINE COMPOUND OF THE FOLLOWING GENERAL FORMULA:
 5. A POLYMETHINE COMPOUND OF THE FOLLOWING FORMULA: 